Comparison of reproductive performance of dairy cattle following a multivalent modified live post-partum vaccine protocol or a multivalent killed pre-partum vaccine protocol
Keywords:reproductive performance, modified live vaccination, killed virus vaccination
Reproductive performance has a major impact on productive efficiency, culling decisions, and profitability of dairy herds. Vaccination of beef cows with a modified live vaccine (MLV) before artificial insemination (AI) has been shown to reduce pregnancy per AI (P/AI) compared with cows that received a killed vaccine (KV). Although a previous experiment with dairy cows showed no difference in P/AI following postpartum vaccination with KV and MLV, the impact of replacing postpartum vaccination with the use of KV prepartum has not been evaluated. The hypothesis of this experiment was that prepartum vaccination with KV improves reproductive efficiency compared with postpartum vaccination with MLV. Therefore, objectives were to evaluate P/AI and pregnancy loss following first AI postpartum, and the hazards of pregnancy and culling by 150 days in milk (DIM) in lactating dairy cows receiving one of two vaccination protocols.